1. Field of the Invention
The present invention relates to a toy building set comprising a number of shafts and a number of toothed wheels, and wherein the shafts are provided with splines for mounting of one or more toothed wheel(s), said toothed wheels having a central opening for receiving the spline of the shaft, and wherein the central opening of the toothed wheels is configured with one or more protruding flanges that engage with one or more of the grooves on the shaft's spline in order to ensure that the toothed wheels mounted on a shaft are unable to rotate relative to said shaft, and wherein the toothed wheels have a number of teeth which corresponds to an entire multiple of the number grooves on the shaft's spline.
2. Description of the Prior Art
Such toy building sets are often combined with a view to building model cranes, cars, machines or other devices in which shafts and toothed wheels are used to form a variety of gear functions and movement functions in the finished model.
In case of conventional gear functions where an input shaft can eg be rotated as much as an infinite number of times about its longitudinal axis, and wherein the sole purpose of the gear transmission is to rotate an output shaft a number of times which is proportional to the input shaft, most frequently correct mounting of shafts and toothed wheels presents no problems, but in situations where the input shaft and output shaft of the gear are connected to functional elements in the toy building set, and where these functional elements are required to have an entirely specific mutual pattern of movement, increased requirements are made to the mounting of a gear by use of the individual toothed wheels and shafts.
Therefore, in particular in connection with these latter toy building sets, building manuals are often included to instruct the user how to build individual models. It is a frequent problem with these manuals to ensure that the user is in fact capable of building the model in such a manner that the functions of the finished model corresponds to the intentions of the manufacturer.
As mentioned above, this is a problem in particular in the construction of models where it is a precondition for obtaining a satisfactory functioning of the toy that gear elements, if any, in the toy building set are correctly assembled, since it is difficult to clearly indicate in the building manual the orientation of a relevant toothed wheel relative to the shaft on which it is mounted to ensure that the toy model functions correctly. In that case, it requires much of the building manual and of the user who is to understand it.
U.S. Pat. No. 2,406,759 describes a toothed wheel for use with toys with which this problem is solved, the toothed wheel shown being provided with four teeth and a square opening for receiving a shaft. Hereby it is made impossible that the toothed wheel is mounted incorrectly on the shaft, which means that gear connections will always be assembled correctly without making substantial requirements to the user or the building manual, while simultaneously avoiding the need for special pairs of associated shafts and toothed wheels, which would reduce the flexibility of the toy and optionally entail increased production costs for the toys.
However, it is a problem with the transmissions that can be built in connection with such toothed wheels that, on the one hand, it is desired to have relatively few teeth and grooves on the toothed wheels and the shafts and, on the other hand, to obtain small wear on the tooth surfaces and an evenly rotating transmission.